IPv6 - Latest Seminar Topics for Engineering CS|IT|ME|EE ... · start with binary value 001 ......

IPv6

CCNA Exploration version 4.0

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Overview

• IP version 6 (IPv6) was developed to overcome the limitations of the current standard, IP version 4 (IPv4). IPv4 allows end systems to communicate and forms the foundation of the Internet as we know it today. However, one of the major shortcomings of IPv4 is its limited amount of address space. The explosion of new IP-enabled devices and the growth of undeveloped regions have fueled the need for more addresses.

• In the United States, the Department of Defense (DoD) is a primary driver for the adoption of IPv6.


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Introducing IPv6

• IP version 6 (IPv6) combines expanded addressing with a more efficient and feature-rich header to meet the demands for scalable networks in the future.

• One key benefit is that IPv6 can recreate end-to-end communications without the need for Network Address Translation (NAT)

• Cisco Systems currently supports IPv6 in Cisco IOS Software Release 12.2(2)T and later.






IPv6 Features






Large Address Space






• IPv6 routers do not perform fragmentation. Instead, a discovery process determines the optimum maximum transmission unit (MTU) to use during a given session.

• Link-layer technologies already perform checksum and error control. Because link-layer technologies are relatively reliable, an IP header checksum is considered to be redundant.






Comparing IPv4 and IPv6 Headers

• Flow Label: 20-bit field that allows a particular flow of traffic to be labeled. It can be used for multilayer switching techniques and faster packet-switching performance.

• Extension Headers: Follows the previous eight fields. The number of extension headers is not fixed, so the total length of the extension header chain is variable.

Traffic class: ToSPayload LengthNext Header: Tcp, Udp…Hop Limit: TTLNo Checksum






Extension Header

Extension Header






IPv6 Extension Headers

• IPv6 Header: Basic header described in the previous figure. • Hop-by-hop options header• Destination options header (when the routing header is used)• Routing header: Used for source routing and mobile IPv6 (value =

43). • Fragment header: Used when a source must fragment a packet that is

larger than the MTU for the path between itself and a destination device.

• Authentication header and Encapsulating Security Payload header: Used within IPsec to provide authentication, integrity, and confidentiality of a packet. The authentication header (value = 51) and the ESP header (value = 50)

• Upper-layer header: Typical headers used inside a packet to transport the data. The two main transport protocols are TCP (value = 6) and UDP (value = 17).






Defining Address Representation

• Leading zeros in a field are optional, so 09C0 = 9C0 and 0000 = 0.• Successive fields of zeros can be represented as “::” only once in an

address. • An unspecified address is written as “::” because it contains only zeros.






IPv6 Address types

• Unicast address– Link local: FE80::/10, Scope is configured to single link. The

address is unique only on this link, and it is not routable off the link. (similar to 169.254.x.x private address)

– Site local: FEC0::/10 (similar to private address)– Global: Globally unique, so it can be routed globally with no

modification. A global address has an unlimited scope on the worldwide Internet. Packets with global source and destination addresses are routed to their target destination by the routers on the Internet.

• Multicast address: IPv6 does not have broadcast addresses. The range of multicast addresses in IPv6 is larger than in IPv4. For the foreseeable future, allocation of multicast groups is not being limited.

• Anycast address: An anycast address identifies a list of devices or nodes; therefore, an anycast address identifies multiple interfaces. A packet sent to an anycast address is delivered to the closest interface, as defined by the routing protocols in use.






Special Address






IPv6 Global Unicast and Anycast address

• Global unicast addresses are defined by a global routing prefix, a subnet ID, and an interface ID. The current global unicast address assignment by the Internet Assigned Numbers Authority (IANA) uses the range of addresses that start with binary value 001 (2000::/3), which is one-eighth of the total IPv6address space and is the largest block of assigned block addresses.

• Addresses with a prefix of 2000::/3 (001) through E000::/3 (111), with the exception of the FF00::/8 (1111 1111) multicast addresses, are required to have 64-bit interface identifiers in the extended universal identifier (EUI)-64 format.

• When a unicast address is assigned to more than one interface, thus turning it into an anycast address, the nodes to which the address is assigned must be explicitly configured to use and recognize the anycast address.






IPv6 Global Unicast and Anycast address






Defining Host Interface Addresses

• An IPv6 address has two parts:– A subnet prefix representing the network to which the interface is

connected. The subnet prefix is a fixed 64-bit length for all current definitions.

– A local identifier, sometimes called a token, which uniquely identifies the host on the local network. The local identifier is always 64 bits and is dynamically created based on Layer 2 media and encapsulation. In the simple case of an Ethernet medium, the local identifier is usually derived from the EUI-48 MAC address.






Link Local Address

• The address is unique only on this link, and it is not routable off the link. Packets with a link-local destination must stay on the link where they were generated

• Link-local addresses are dynamically created using a link-local prefix of FE80::/10 and a 64-bit interface identifier in a process called stateless autoconfiguration.






Stateless Autoconfiguration

• Phase 1: MAC 00-0C-29-C2-52-FF -> 00-0C-29-FF-FE-C2-52-FF

• Phase 2: well-known link-local prefix fe80::/64 is added -> fe80::00c:29ff:fec2:52ff

• Phase 3: Verify the address’s uniqueness on the link, called duplicate address detection (DAD). Send ICMPv6.

• Phase 4: Assigned






IPv6 Multicast Address






IPv6 Multicast Address

• FF02::1:FFXX:XXXX — Solicited-node multicast on link, where XX:XXXX is the rightmost 24 bits of the corresponding unicast or anycast address of the node. (Neighbor solicitation messages are sent on a local link when a node wants to determine the link-layer address of another node on the same local link, similar to Address Resolution Protocol [ARP] in IPv4.)






IPv6 Routing

• Similar to IP version 4 (IPv4) classless inter-domain routing (CIDR), IPv6 uses longest-prefix match routing.

• Routing protocol: RIPng, OSPFv3, EIGRP, ISIS, MP-BGP• Static routing: A router must be able to determine the link-

local address of each of its neighboring routers to ensure that the target address of a redirect message identifies the neighbor router by its link-local address.






RIPng

• Based on IPv4 RIP version 2 (RIPv2) and similar to RIPv2 • Uses IPv6 for transport • IPv6 prefix, next-hop IPv6 address • Uses the multicast group FF02::9, the all-RIP-routers

multicast group, as the destination address for RIP updates • Updates sent on UDP port 521 • Command:

– Router(config)#ipv6 router rip bkacad– Router(config-router)#maximum-paths 2– Router(config)#interface fa0/0– Router(config-if)ipv6 rip bkacad enable






IPv6 to IPv4 Transition Mechanism

• The two most common techniques to transition from IPv4 to IPv6 are as follows:– Dual stack – IPv6-over-IPv4 (6to4) tunnels

• For communication between IPv4 and IPv6 networks, IPv4 addresses can be encapsulated in IPv6 addresses.






Cisco IOS Dual Stack

• Using IPv6 on a Cisco IOS router requires that you use the global configuration command ipv6 unicast-routing. This command enables the forwarding of IPv6 datagrams.






• A dual-stack node chooses which stack to use based on the destination address. A dual-stack node prefers IPv6when available.

• A new application programming interface (API) is defined to support both IPv4 and IPv6 addresses and Domain Name System (DNS) requests.

• Past experience in porting IPv4 applications to IPv6suggests that for most applications it is a minimal changein some localized places inside the source code.






Overlay Tunnels

• Tunneling IPv6 traffic over an IPv4 network requires one edge router to encapsulate the IPv6 packet inside an IPv4 packet and another router to de-encapsulate it.

• Tunneling is an integration method where an IPv6 packet is encapsulated within another protocol, such as IPv4.






• This method of encapsulation is IPv4 protocol 41 and has the following characteristics:

• Includes a 20-byte IPv4 header with no options and an IPv6 header and payload.

• Considered dual stacking, which enables the connection of IPv6 islands without converting an intermediary network to IPv6.

• Tunneling presents these issues:– The MTU is decreased by 20 octets (if the IPv4 header does not

contain any optional field). – Difficult to troubleshoot.






• Encapsulation can be done by edge routers between hosts or between a host and a router.

• Tunneling does not work if an intermediary node between the two end points of the tunnel, such as a firewall, filters out IPv4 protocol 41, which is the IPv6-over-IPv4 encapsulation.






Example of Configure

• The command that enables the IPv6 overlay tunnel is tunnel mode ipv6ip.

192.168.30.1






6to4 tunneling

• The 6to4 tunneling method automatically establishes the connection of IPv6 islands through an IPv4 network.

• Each 6to4 site receives a /48 prefix, which is the concatenation of 0x2002 and the hexadecimal IPv4 address of the edge router.

• In Figure , the IPv4 address of the edge router is 192.168.99.1. As a result, the prefix of its IPv6 network is 2002:c0a8:6301::/48 because c0a86301 is the hexadecimal representation of 192.168.99.1. The IPv6 network can substitute any IP address in the space after the first 16-bit section (0x2002).






NAT-Protocol Translation (NAT-PT)






• Several other automatic tunneling transition mechanisms exist, including these:– 6to4: Uses the reserved prefix 2002::/16 to allow an

IPv4 Internet-connected site to create and use a /48 IPv6 prefix based on a single globally routable or reachable IPv4 address.

– Intra-Site Automatic Tunnel Addressing Protocol (ISATAP): Allows an IPv4 private intranet (which may or may not be using RFC 1918 addresses) to incrementally implement IPv6 nodes without upgrading the network.






LAB

ipv6 unicast-routinginterface lo0

ipv6 address 2003::1/64ipv6 rip bkacad enable

interface f0/0ipv6 address 2fff::1/64ipv6 rip bkacad enable

interface s1/0ipv6 address 2004::1/64ipv6 rip bkacad enable

R1 R2S1/0S1/1F0/0

L0 L0

2004::1/64 2004::2/642003::1/64 2005::2/64

2fff::1/64

2fff::2/64

ipv6 unicast-routingIpv6 route ::/0 lo0interface lo0

ipv6 address 2003::1/64ipv6 rip bkacad enable

interface f0/0ipv6 address 2fff::1/64ipv6 rip bkacad enable

interface s1/0ipv6 address 2004::1/64ipv6 rip bkacad enable

ipv6 router rip bkacadredistribute staticipv6 install

netsh interface ipv6 add address "Local Area Connection" 2fff::2





IPv6 - Latest Seminar Topics for Engineering CS|IT|ME|EE ... · start with binary value 001 ......

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